1. Field of the Invention
This invention relates to an improved balloon catheter and, more specifically, to a catheter incorporating means adapted to prevent the sticking of the expandable member or balloon to the catheter. In another aspect, the invention relates to a catheter for use in coronary bypass surgery positioned externally of the heart and adapted to assist in the retention of a retrograde cardioplegia solution perfusion ("RCSP") catheter in the coronary sinus.
2. Description of the Related Art
Catheters having an expandable member provided thereon have a wide variety of applications in numerous, different, medical procedures. One known structure for such a catheter comprises an expandable member or balloon provided on the outside surface thereof wherein the balloon is expandable between a retracted state and an expanded state. In the retracted state, the balloon can be a "tight-fitting" balloon which is inflated through the application of a pressurized fluid to the interior of the balloon. One problem inherent with such tight-fitting balloons is the uneven inflation of the balloon upon the application of a pressurized fluid to the balloon interior. In drastic cases, portions of the balloon remain tacked to the exterior surface of the catheter body when the balloon is in the fully-inflated position. This can result in the balloon, in the expanded shape, assuming an undesirable, unpredictable configuration. In addition, tacking of the balloon can result in excessive elongation of portions of the balloon body.
As noted above, balloon catheters have a wide variety of applications, only one of which is used during coronary bypass surgical procedures. Perfusion of a heart during coronary bypass surgery with cardioplegia solution can be performed retrograde, antigrade, or a combination of retro and antigrade. During the retrograde profusion process, a catheter is first typically inserted into the right atrium through an appropriate incision and then inserted through the ostia into the coronary sinus. Next, an expandable member, such as a balloon which is provided on the catheter, is inflated inside the coronary sinus to occlude this vessel. Cardioplegia solution is forced through the catheter into the coronary sinus to perfuse the heart tissue. Examples of known retrograde catheters are seen in U.S. Pat. No. 5,395,330 issued Mar. 7, 1995 to Marcadis et al. and U.S. Pat. No. 5,505,698 issued Apr. 9, 1996 to Booth et al.
One problem with the known RCSP process is possible movement or dislodging of the RCSP catheter from the coronary sinus as a result of the fluid pressure generated inside the coronary sinus. Excessive movement of the inflated RCSP catheter could result in leaking of cardioplegia solution from the coronary sinus back into the right atrium.
Another problem experienced by some patients during the retrograde perfusion process is insufficient perfusion of the heart tissue as a result of leaking of solution from the middle cardiac vein and the small cardiac vein back into the right atrium. When perfusion solution is allowed to drain from the veins back into the right atrium, the cardioplegia solution being perfused through the tissue will seek the path of least resistance and drain into these veins rather than completely perfusing the heart tissue.